I. Field of the Invention
The present invention relates to wireless communication. More particularly, the present invention relates to method and apparatus for providing configurable layers and protocols in a communications system.
II. Description of the Related Art
The use of code division multiple access (CDMA) modulation techniques is one of several techniques for facilitating communication in which a large number of system users are present. Although other multiple access communication system techniques are known in the art, such as time division multiple access (e.g., TDMA and GSM), frequency division multiple access (FDMA), and AM modulation schemes such as amplitude companded single sideband (ACSSB), the spread spectrum modulation techniques of CDMA have significant advantages over these other modulation techniques for multiple access communications systems. The use of CDMA techniques in a multiple access communications system is disclosed in U.S. Pat. No. 4,901,307, entitled “SPREAD SPECTRUM MULTIPLE ACCESS COMMUNICATION SYSTEM USING SATELLITE OR TERRESTRIAL REPEATERS,” issued Feb. 13, 1990, and U.S. Pat. No. 5,103,459, entitled “SYSTEM AND METHOD FOR GENERATING SIGNAL WAVEFORMS IN A CDMA CELLULAR TELEPHONE SYSTEM,” issued Apr. 7, 1992, both assigned to the assignee of the present invention and incorporated herein by reference.
CDMA systems are typically designed to conform to one or more particular CDMA standards. Examples of such CDMA standards include the “TIA/EIA/IS-95-A Mobile Station-Base Station Compatibility Standard for Dual-Mode Wideband Spread Spectrum Cellular System,” the “TIA/EIA/IS-95-B Mobile Station-Base Station Compatibility Standard for Dual-Mode Wideband Spread Spectrum Cellular System,” the TIA/EIA/IS-98-A, -B, and -C standards entitled “Recommended Minimum Performance Standard for Dual-Mode Spread Spectrum Cellular and PCS Mobile Stations,” and “The cdma2000 ITU-R RTT Candidate Submission.” New CDMA standards are continually proposed and adopted for use.
Each CDMA standard defines an air interface protocol used by that standard to support communication between communicating devices (i.e., between an access terminal and a radio network). The air interface protocol defines the mechanisms by which particular functions are to be performed, and may encompass a number of protocols that enable implementation of various functions.
Conventionally, each CDMA standard adopts a particular air interface protocol that performs a number of functions and is identified by a unique revision number. New functions can be implemented by defining new attributes, messages, and state machines, usually within the framework of the existing air interface protocol. A new air interface protocol is then defined that includes the new attributes, messages, and state machines along with other previously defined attributes, messages, and state machines. Similarly, if an existing protocol is modified or updated, a new air interface protocol is defined and a new revision is assigned.
Conventionally, each communicating device (e.g., each access terminal and radio network) is designed to support one or more complete revisions of the air interface protocol. Because the entire air interface protocol is defined by a single revision, each communicating device is required to support all required functions in a particular revision if it wishes to support any function in that revision. The communicating devices are typically designed to support one or more revisions (e.g., a range of revisions). Communication between the access terminal and radio network is then achieved using any one of the commonly supported air interface protocol revisions.
The desire for increased wireless functionality and capacity has resulted in ever more complex air interface protocols. In particular, the air interface protocols have evolved to perform numerous complex functions, including voice communication, data transmission, and so on.
The conventional method of defining a new revision for each new air interface protocol was adequate for more “simple” protocols in the original CDMA system design. As the number of functions and their complexity increase, the conventional method is cumbersome and inadequate. The conventional method also does not easily support the implementation of additional functions in an existing air interface protocol or implementation of a subset of the functions in the air interface protocol.
Thus, an air interface protocol structure that efficiently supports implementation of a variety of functions is highly desirable.